Trial Frame

ABSTRACT

The invention relates to a trial frame for determining the subjective refraction of a subject, comprising two lens holder devices for receiving lenses, a bridge, which adjustably connects the lens holder devices, a nose rest device having a pivotable and height-adjustable nose rest and two temples, which are adjustable in length and height, the trial frame comprising two polarization filter devices, the polarization filter devices having a circular or a linear polarization filter, a pivot for pivoting the circular or linear polarization filter in and out in front of the lens holder device, and a rotating device for rotating the polarization filter in front of the lens holder device, the polarization filter devices each being removably attachable to the lens holder devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of German Utility Model ApplicationNo. 20 2015 106 765.8 filed Dec. 11, 2015. The contents of which ishereby incorporated by reference as if set forth in its entirety herein.

FIELD OF THE INVENTION

The invention relates to a trial frame for determining the subjectiverefraction of a subject, comprising two lens holder devices forreceiving insert lenses, a bridge, which connects the lens holderdevices in such a manner that their distance relative to each other isadjustable, a nose rest device having a pivotable and height-adjustablenose rest, and two temples, which are adjustable in length and height,the nose rest device having an adjustment gear for adjusting the heightof the nose rest.

BACKGROUND OF THE INVENTION

Trial frames of this kind are typically used to determine ophthalmiclenses. To do so, the trial frame is adjusted to a subject, that is aperson, and easily exchangeable insert lenses or trial lenses areinserted into the trial frame. The insert lenses are arranged in arotatable manner so as to be able to correct astigmatic defects in theiraxial position. Lateral defects and height defects, which are correctedby means of prisms, have to be adjustable as well, which is why thetrial frame has to be precisely adjusted to a subject or patient. Forexample, a pupil distance has to be adjustable, wherein a pupil centerof each eye is supposed to be adjustable in a separate manner. A heightof the trial frame is adjusted via the nose rest, which is also arrangedon the bridge in a pivotable manner. By pivoting the nose rest andadjusting the length of the temples, a distance of the trial frame inrelation to the eyes can be adjusted. For adjustment to different earshapes, the temples are pivotable in height and laterally. A trial frameof this kind is known from EP 0 567 817 B1, for instance.

Since the examining person will always adjust the trial frameimmediately on the head of the subject, the operating elements of thetrial frame have to be easy to operate and they need to be arranged in amanner that allows ergonomic handling. At the same time, the subjectshould not be unnecessarily bothered by the operation of the trial frameduring adjustment of the trial frame. For instance, catching of thesubject's hair in the trial frame and hand movements within the closerfield of vision are undesired.

Because of the various adjustment options, the known trial frames arecomposed of a plurality of individual parts, which makes manufacture ofthe trial frame complex. For instance, height adjustability of the noserest typically requires an adjustment gear, said adjustment gear beingcomposed of a plurality of gear elements or gear wheels for converting arotational adjusting motion into a translational motion of the nose restat a desired gear ratio.

With the known trial frames, the lens holder devices are displaced bymeans of threaded spindles arranged within the bridge in order to adjustthe pupil distance. For this purpose, spindle nuts are formed orarranged on the lens holder devices. For instance, it is known for alens holder device to be produced in a plastic injection-molding processand for the threaded nut to be molded to the lens holder device. To doso, a threaded spindle is injection-coated in a mold, the threadedspindle having to be unscrewed from the threaded nut in order to demoldthe lens holder device. Because of cooling or mold shrinkage of theplastic material, however, the threaded nut may become deformed in sucha manner that a thread for the threaded spindle will have to berethreaded.

Also, in the case of some trial frames, the bridge is made of a metaltube into which a groove is milled. Inner flanks of this groove serve asa longitudinal guide for the lens holder devices, allowing the lensholder devices to be transversally displaced. The guide means thusformed has to exhibit a comparatively precise fit in order to precludesagittal tilting of the lens holder as far as possible. Hence, aftermilling of the groove, the bridge has to be routinely refinished inorder to form the desired loose fit. These necessary manufacturingsteps, too, are relatively time-consuming.

Trial frames are also employed together with polarization filterdevices, which can be used for eyesight tests in combination with apolarized display of optotypes. Depending on the type of polarization ofthe optotypes, circular or linear, corresponding polarization filtersare needed on the trial frame. However, these polarization filtersrequire different handling, which means that the trial frame has to bedesigned according to said handling.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a trialframe that is flexible in use.

The trial frame according to the invention for determining thesubjective refraction of a subject comprises two lens holder devices forreceiving insert lenses, a bridge, which connects the lens holderdevices in such a manner that their distance relative to each other isadjustable, a nose rest device having a pivotable and height-adjustablenose rest, and two temples, which are adjustable in length and height,the trial frame comprising two polarization filter devices, thepolarization filter devices having a circular or a linear polarizationfilter, wherein the polarization filter devices having the circular orlinear polarization filter each have a pivot means for pivoting thecircular or linear polarization filter in and out in front of the lensholder device, the polarization filter devices having the linearpolarization filter each having a rotating means for rotating the linearpolarization filter in front of the lens holder device, the polarizationfilter devices each being removably attachable to the lens holderdevices by means of a locking connection.

The positional and directional terms indicated below always relate tothe body or the body planes of a subject or patient to whom the trialframe is adjusted.

Depending on the polarization of optotypes used, the circular or thelinear polarization filter can be selected. The circular and the linearpolarization filter can each be pivoted into or out of a subject's fieldof vision in front of the lens holder device by means of the pivot meansin order to be able to perform the corresponding eyesight test. If thepolarization filter device is equipped with the linear polarizationfilter, the rotating means is further provided to rotate the linearpolarization filter in front of the lens holder device or the subject'sfield of vision. The pivot means can be realized with a hinge thatallows radial or axial pivoting of the polarization filter relative tothe subject's optical axis. The rotating means can be realized with anaxis that allows radial or axial rotating of the linear polarizationfilter relative to the subject's optical axis. This allows changing anorientation or direction of polarization. Thus, use of the polarizationfilter devices is flexible depending on the polarization of theoptotypes.

Since the polarization filter devices are supposed to be usable foroptional eyesight tests with the trial frame, they can be removablyattached to the trial frame independently of the lens holder devices.Owing to the fact that this removable attachment happens by means of alocking connection on the lens holder device, the polarization filterdevice can be attached and removed again in a particularly quick andsimple manner. The locking connection can also be designed in such amanner that a clamping force is effected, which prevents undesiredmotion of the polarization filter device on the lens holder device. Inthis case, the locking connection can be realized as a zero-playconnection, allowing the polarization filter device to be operated in aparticularly precise manner.

At an attachment end of a holder of the polarization filter device, aone-piece spring clamp can be formed, which can engage behind acrosspiece molded to the lens holder device, wherein an actuating levercan be molded to the spring clamp or to the attachment end by means ofwhich the spring clamp can be opened. The attachment end can also be inone piece and can be made entirely of plastic and can comprise thespring clamp so as to reduce a number of parts of the trial frame evenfurther. The attachment end can also be realized in the shape of a clawthat engages behind the crosspiece in such a manner that the holder canbe hooked onto the crosspiece. Furthermore, a locking nose or lockingrecess can be molded to the crosspiece or to the spring clamp, intowhich a matching locking recess or locking nose can engage. When theclaw engages the crosspiece at an edge thereof or is hooked into thecrosspiece at said edge, the spring clamp can engage an opposite edge ofthe crosspiece and lock with it. To simplify detachment of the holderand of the spring clamp from the lens holder device and from thecrosspiece, respectively, the actuating lever can be molded to thespring clamp or to the attachment end. The actuating lever can bearranged in such a manner that the spring clamp is bent open and thelocking connection is released when the actuating lever is actuated.

The nose rest device can have an adjustment gear for adjusting theheight of the nose rest, wherein the adjustment gear can have a toothedrack and a bevel worm wheel, which are engaged with each other. Owing tothe fact that the adjustment gear for adjusting the height of the noserest has a toothed rack, the toothed rack can be moved translationally,thus effecting a height adjustment of the nose rest. Furthermore, thetoothed rack easily allows the adjustment gear to be self-locking. Thetoothed rack is engaged with the bevel worm wheel, so that the rotationof the bevel worm wheel causes the translational motion of the toothedrack. Owing to the fact that, with respect to a longitudinal axis of thebevel worm wheel, the bevel worm wheel forms a conical outer diameterwith teeth, the bevel worm wheel can be arranged relative to the toothedrack in such a manner that the longitudinal axis of the bevel worm wheelis arranged at an angle β, which corresponds to half an opening angle αof the bevel worm wheel. In the case of a longitudinal height adjustmentof the toothed rack or in the case of a nose rest height-adjustable in asagittal plane relative to the bridge or lens holder device, the bevelworm wheel will preferably arranged in such a manner that thelongitudinal axis extends in a distal direction. In this way, it becomespossible to adjust the height of the nose rest without a hand of theoperator entering the immediate field of vision of a subject or patient.Moreover, insertion of insert lenses into the lens holder device is notimpeded by an operating element of the adjustment gear in the immediatearea of the nose of the subject. The trial frame is thus easier tohandle and is less bothersome to the subject.

The adjustment gear can be formed by the toothed rack and the bevel wormwheel. In this case, the adjustment gear is formed by only two mobilegear components. Thus, installation of the adjustment gear issubstantially simplified, which allows cost-effective manufacture of thetrial frame. The teeth of the bevel worm wheel can thus run in themanner of a conical thread. Since the nose rest is adjusted manually,only low forces are transmitted via the adjustment gear, which is whysimplified geometries can be used for forming teeth or a teeth geometryof the toothed rack and of the bevel worm wheel.

It is particularly advantageous for the bevel worm wheel to have anopening angle α of 60° to 120°, preferably of 90°. When the bevel wormwheel is then engaged with the toothed rack, the bevel worm wheel isinclined relative to the toothed rack by an angle β of 30° to 60°,preferably of 45°. Since the toothed rack is substantially adjusted in alongitudinal direction, it is further advantageous for the bevel wormwheel to be arranged on the toothed rack in such a manner that it isinclined in a distal direction or upward, allowing an operating elementin connection with the bevel worm wheel to be arranged above a subject'snasal bridge. When the nose rest is being adjusted by an operator, theoperator's actuating hand will thus not be located immediately in frontof the subject's eyes or within the closer field of vision. Moreover,the operating element will thus be arranged in a manner that isergonomically favorable to the operator and will not be in the way whenthe insert lenses are being exchanged.

Furthermore, the bevel worm wheel can have a lead of 1 mm to 3 mm,preferably of 2 mm. Thus, the nose rest can be adjusted by thecorresponding length in a longitudinal direction with a singlerevolution of an operating element of the nose rest device.

The bevel worm wheel can be molded to an actuating shaft, wherein theactuating shaft can then be realized in such a manner that an operatingelement can be plugged directly onto the actuating shaft. For example,the bevel worm wheel can be produced in one piece in aninjection-molding process. Hence, the bevel worm wheel can be made ofplastic or metal. Overall, a number of parts of the trial frame can thusbe reduced further. A distal end of the actuating shaft can be realizedin such a manner that the operating element can be connected to thedistal end in a form-fitting manner. For example, a material recess inthe shape of a segment of a circle can be realized at the distal end, towhich the operating element is fitted. Furthermore, a locking recess ora locking protrusion for a locking connection to the operating elementcan be realized at the distal end.

In this way, the operating element can also be arranged above thebridge, the operating element thus being arranged at the edge or outsideof a subject's field of vision.

Operating elements of the trial frame can be actuated particularly wellif they are cylindrical or frustoconical and made in one piece of aflexible plastic material. In particular when taking hold of afrustoconical operating element by pronating 2 to 3 fingers, theoperating element can be gripped at the largest diameter of the frustumwhen performing fine adjustment or optionally at the circumferentialsurface of the frustum when performing quick adjustment. Moreover, owingto the flexible plastic material, the operating element can be graspedin a haptically pleasant manner and slipping of the operating elementthrough the fingers is prevented. Owing to the one-piece design,production of the operating element is cost-effective and a number ofparts of the trial frame is reduced. For connecting the operatingelement to the actuating shafts or spindles of the trial frame, theoperating element can have a recess for form-fitting plugging with alocking protrusion or a locking recess.

The nose rest device can be mounted on a pivot axis of the bridge bymeans of a radial clamping. A radial clamping can be produced in aparticularly simple manner and can have a ring, for example, whichsurrounds the pivot axis and has a slot or a spring. The radial clampingcan also be adjustable in terms of its clamping force. The substantialaspect is that there is a self-locking clamping of the nose rest deviceon the pivot axis.

The bridge can be formed by two bridge sections, which can be firmlyconnected by means of a pivot axis, wherein the nose rest device can bepivotably mounted on the pivot axis. In a particularly simpleembodiment, the bridge sections can then be connected merely by means ofa pin, which is inserted into the respective bridge sections and formsthe pivot axis. In this case, the outer shape of the bridge sections canbe formed independently of the pivot axis or of the connection to thenose rest device. The bridge sections can be secured to the pivot axisagainst turning or against the pivot axis being pulled out simply bymeans of a screw or by being glued. In this case, it is alsoparticularly advantageous if there is solely an axial clamping of thenose rest device on the pivot axis.

The bridge and the lens holder devices together can form a guide meansfor guiding the mobile lens holder devices in the longitudinal directionof the bridge, wherein the bridge can have a spindle gear, which can beself-locking and can have a threaded spindle for adjusting the distanceof the lens holder devices, wherein at least one guide protrusion can beformed on each of the lens holder devices, said guide protrusion beingable to engage into a guide groove formed in the bridge, wherein openthreaded sections can be formed on the lens holder devices, wherein thethreaded spindle can be engaged with the threaded section. Thus, theguide means can be realized in such a manner that the lens holderdevices are mobile in the longitudinal direction of the bridge, i.e.transversally mobile. In this way, it becomes possible to adjust arelative distance of the lens holder devices so as to adjust the trialframe to a pupil distance. This distance adjustment can take place viathe spindle gear, which has at least one threaded spindle. There may bea single threaded spindle with opposite threads in threaded sections forboth lens holder devices or each lens holder device may have its ownthreaded spindle. The threaded spindle will then engage into a threadedsection of the lens holder device, wherein the threaded section can beopen, which means that the threaded section is realized in the manner ofa toothed rack or has a sector of a threaded bore at the lens holderdevice. In that case, the threaded section can be formed integrally withthe lens holder device, for instance in one piece by injection molding.By means of a rotational motion of the threaded spindle, a translationalmotion of the lens holder device along a longitudinal axis of the bridgecan be caused. Cumbersome demolding of the lens holder device or apotentially required rethreading of the threaded section is no longernecessary. The guide protrusion can also be molded to the lens holderdevice. The guide protrusion can preferably be arranged on a sidesurface of the lens holder device, wherein another guide protrusion canalso be arranged on an opposite side surface or multiple guideprotrusions can be arranged on one side surface. The substantial aspectis that the guide protrusion engages into the guide groove which can beformed in the bridge. Aside from guide surfaces of the guide means,which can be in contact with side surfaces of the lens holder device,the guide protrusion and the guide groove form other guide surfaces,which can ensure a substantially zero-play guiding of the lens holderdevices in the bridge. Radial tilting of the lens holder devicesrelative to the threaded spindle, as known from the state of the art,can be effectively prevented in this way.

The bridge can have a longitudinal slot which forms parallel guidesurfaces for the lens holder devices, wherein the guide groove can beformed on or in at least one of the guide surfaces. The guide surfacesof the longitudinal slot can then be in contact with side surfaces ofthe lens holder devices. A longitudinal slot can be formed in one of theguide surfaces or also in both guide surfaces, wherein the longitudinalslot can be formed to match the guide protrusion or guide protrusions.The guide groove can be formed in the manner of a rectangular taperingor semicircular groove. The guide grove consequently also prevents thelens holder devices from dropping out of the longitudinal slot. Sagittaltilting of the lens holder devices can be effectively prevented inparticular by the horizontal guide surfaces of the guide means formedbetween the guide groove and the guide protrusion. A particular accuracyof fit of the longitudinal slot is no longer required in this case.

In particular, a passage bore for receiving the threaded spindle can beformed in the longitudinal direction of the bridge, the passage borebeing adjacent to the longitudinal slot. The longitudinal slot thusprotrudes into the passage bore, and a diameter of the passage bore canbe the same as or larger than a width of the longitudinal slot. Also,assembly of the trial frame is substantially simplified by the fact thatthe threaded spindle has to be inserted into the passage bore with thelongitudinal slot together with the lens holder device.

It is particularly advantageous if a plurality of crosspiece-shapedguide protrusions is formed on the lens holder device. Thecrosspiece-shaped guide protrusions can be arranged on both sidesurfaces of the lens holder device. For example, two spaced-apartcrosspiece-shaped guide protrusions can be arranged or formed on oneside surface and a single crosspiece-shaped guide protrusion can bearranged or formed on an opposite side surface. The resulting rest ofthe lens holder device on three support points of the guide meansprevents the lens holder device from becoming wedged or jammed in theguide groove.

Production of the trial frame becomes especially cost-effective if thebridge is formed by an extruded profile. The extruded profile canadvantageously have the cross-section of the bridge from the start, thusrequiring no finishing work or only insignificant finishing work on theextruded profile. Since there may consequently be no need for millingwork on the extruded profile, the problem of bending open thelongitudinal slot is avoided. Moreover, an extruded profile made ofaluminum or titanium, for example, is available at low cost.

The threaded spindle can be mounted radially on an inner bearing andradially and axially on an outer bearing. Hence, the inner bearing canbe realized as a loose bearing and the outer bearing can be realized asa fixed bearing of the threaded spindle. The inner bearing can be aplastic bushing, which is merely inserted into a bore in the bridge forreceiving the threaded spindle. The outer bearing can be made ofplastic, wherein the outer bearing can be firmly fixed to an outertransversal end of the bridge. This way of mounting the threaded spindleis made necessary by, among other things, the fact that the lens holderdevice does not have a closed thread. In case the inner bearing ismerely a plastic bushing, its added costs are easily compensated for bythe simplified demolding of the lens holder device alone.

The outer bearing can engage into the guide groove in a form-fittingmanner. Thus, it is possible to prevent radial rotation of the outerbearing and to also secure the outer bearing against axial motions, forinstance by means of a clamping fit in the guide groove. Optionally, itmay also be envisaged for the outer bearing to be fixed to the bridge bya screw connection. The outer bearing can be produced by plasticinjection molding.

The lens holder device can have a rotatable ring on which lens seats areformed, wherein an actuating shaft of a ring can have an adjustablebraking means, wherein the braking means can be an eccentric plasticring. The rotatable ring having the lens seats can be made of plastic orlight metal, wherein a gear wheel of the actuating shaft can engage intoteeth formed on the rotatable ring, the rotatable ring thus beingrotatable by means of a rotation of the actuating shaft. In this case,the actuating shaft is arranged in such a manner that it extends in thedirection of a center of the ring. To prevent unintentional rotation ofthe ring, the plastic ring can surround the actuating shaft so that arotation resistance of the actuating shaft can be formed. In case theplastic ring is eccentric, a larger or a smaller rotation resistance canbe set as needed through radial rotation of the plastic ring on theactuating shaft.

The lens holder devices can each have four front and two rear lensseats. The plurality of front or ventral and rear or dorsal lens seatsoffers particularly versatile usage of the trial frame. For instance, aseries of insert lenses, for correcting short-sightedness,long-sightedness and astigmatism, for example, can be usedsimultaneously. The lens seats can each be formed by at least two orthree crosspieces that can support the insert lenses at theircircumference.

The lens seats of the lens holder devices can each have at least onepressure finger for clamping an insert lens, the respective pressurefingers being arranged in a row at the lens holder device and beingsubjectable to a contact pressure force via a shared leaf spring. Incase the lens seats are realized in the shape of crosspieces, onepressure finger per insert lens can be formed or arranged on one of thecrosspieces. From the state of the art, it is known for these pressurefingers to each be subjected to the contact pressure force by means ofindividual leg springs made of spring wire. In order to reduce a numberof parts of the trial frame and to simplify assembly, it is henceadvantageous to use a single leaf spring instead of a plurality of legsprings. This requires that the pressure fingers are always arrangedadjacent and in a row on the lens holder device. The leaf spring canalso be realized in such a manner that the leaf spring forms multiplefinger-shaped leaf-spring sections, which each act on one pressurefinger alone.

Temple ends of the temples can each be flexible, wherein each temple endcan also be loop-shaped. The dorsal temple ends of the temples canadvantageously form a sickle-shaped or crescent-shaped loop, which canengage behind an ear or an antihelix in order to thus prevent the trialframe from dropping from a subject's head. The loop-shaped design of thetemples ends provides them with flexibility and allows them to adjustespecially well to an ear, preventing pressure marks on the ear thatwould be uncomfortable to a subject. The flexible design of the templeends is simplified if the temples ends are made of an at least partiallyflexible moldable plastic material.

Temple ends of the temples can each be made in one piece and of a softand a comparatively hard plastic material. It may be envisaged for thedorsal temple ends to be made of the soft plastic material and for thetemple itself to be made of the hard plastic material at least insections. Manufacture of the temple by means of plastic injectionmolding will thus be cost-effective and simple. The soft plasticmaterial can be flexible, thus preventing pressure marks on a subject'sear. At least one straight temple section adjacent to the dorsal templeend can then be made of the comparatively hard plastic material becausethis temple section also has to be comparatively stiff. The templesection can also end in a metal temple section towards a ventral, fronttemple end. Both temple sections can be designed in such a manner thatthey can be telescoped into each other.

A front or ventral end of the temple can be cranked. This allows thetemple to be arranged on the lens holder devices as deeply as possible,i.e. in the proximal direction. An operator will thus be able to inspectthe eyes from the side and to put insert lenses into rear lens seatswithout hindrance. Also, a distance between the trial frame and the eyescan thus be adjusted and measured more easily by the operator. Owing tothe fact that the temple or its ventral end is cranked, the temple doesnot have to be significantly inclined in relation to a horizontaltransversal plane, which means that the temple is adjustable to an earas usual.

Hereinafter, a preferred embodiment of the trial frame is explained inmore detail with the aid of the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing:

FIG. 1 shows a perspective view of a trial frame;

FIG. 2 shows the trial frame with attached polarization filter devices;

FIG. 3 shows a front view of the trial frame;

FIG. 4 shows a rear view of the trial frame;

FIG. 5 shows a lateral view of the trial frame;

FIG. 6 shows a lateral view of the trial frame with attachedpolarization filter devices;

FIG. 7 shows a top view of the trial frame;

FIG. 8 shows a perspective detail illustration of a lens holder devicehaving a threaded spindle;

FIG. 9 shows a partial illustration of a lens holder device on a bridge;

FIG. 10 shows a section view along line X-X of FIG. 9;

FIG. 11 shows a partial illustration of the lens holder device and ofthe bridge of FIG. 9 in a lateral view;

FIG. 12 shows a section view along line XII-XII of FIG. 11;

FIG. 13 shows a bottom view of a nose rest device;

FIG. 14 shows a lateral view of the nose rest device;

FIG. 15 shows a rear view of the nose rest device; and

FIG. 16 shows a cross-section view of the nose rest device.

DETAILED DESCRIPTION OF THE INVENTION

A combined view of FIGS. 1 to 7 shows a trial frame 10 in differentviews. In the illustrations of FIGS. 2 and 6, polarization filterdevices 11 of the trial frame 10 are attached to the same. The trialframe 10 serves to determine the subjective refraction of a subject orpatient (not illustrated). Hence, directional and positional terms belowalways relate to body planes of a subject wearing an adjusted trialframe 10. The trial frame 10 comprises two lens holder devices 12 and 13for receiving insert lenses (not illustrated) and a bridge 14, whichconnects the lens holder devices 12 and 13 at a distance relative toeach other in the transversal direction in an individually adjustablemanner. The bridge is formed by two bridge sections 15 and 16, which arefirmly connected to each other by means of a pivot axis 17. Accordingly,lens holder device 12 is adjustably attached to bridge section 15 andlens holder device 13 is adjustably attached to bridge section 16.Furthermore, the trial frame 10 comprises a nose rest device 18 having anose rest 19. The nose rest device 18 or the nose rest 19 is mounted onthe pivot axis 17 so as to be radially pivotable in a sagittal planerelative to the bridge 13 or to the lens holder device 12 and 13.Furthermore, the nose rest 19 is height-adjustable in the longitudinaldirection relative to the bridge 14 or to the lens holder devices 12 and13. Height adjustment is made possible by an adjustment gear 20. Thetrial frame 10 further comprises two temples 21 and 22, which arearranged in a mobile manner on crosspieces 23 and 24 formed by the lensholder devices 12 and 13, respectively. The temples 21 and 22 arelength-adjustable relative to the bridge 14 or to the lens holderdevices 12 and 13 and height-adjustable in the longitudinal direction.

The temples 21 and 22 have flexible temple ends 25 and 26, respectively,which are formed in one piece together with a temple section 27 and 28,respectively. The temple ends 25 and 26 consist of a soft plasticmaterial and the temple sections 27 and 28 consist of a comparativelyhard plastic material. The temple ends 25 and 26 are produced togetherwith the temple sections 27 and 29, respectively, in a shared mold in aninjection-molding process. The temple ends 25 and 26 each form asickle-shaped loop 29 and 30, respectively, ventral loop sections 31coming into contact with an ear or antihelix and dorsal loop sections 32ensuring elastic deformation of the temples ends 25 and 26 in the mannerof a spring. In this way, the temple ends 25 and 26 adjust particularlywell to a subject's ear. The temple sections 27 and 28 are eachconnected to a guide rod 33 in a longitudinally mobile manner, allowingthe temples 21 and 22 to be adjusted in length. To simplify manuallength adjustment, actuating protrusions 34 are molded to each of thetemple sections 27 and 28. Furthermore, ventral ends 35 and 36 of thetemples 21 and 22, respectively, are designed with a cranked section 37and 38, respectively. The sections 37 and 38 are each pivotably attachedto axes 39 at the crosspieces 23 and 24, respectively, translucent rules40 and 41 being attached to the sections 37 and 38, respectively. Therules 40 and 41 can be used to measure the distance relative to an eyeor to its apex. The sections 37 and 38 are further connected to theguide rods 33 via pivot means 42 for adjusting an inclination of thetemple ends 24 and 26 in the longitudinal direction. Thus, the temples21 and 22 can be adjusted and adjusted to a subject's head in threedirections, namely transversally, longitudinally and sagittally.

The polarization filter devices 11 are each removably attached to thelens holder devices 12 and 13 by means of a locking connection 43. Onholders 44 and 45 of the polarization filter devices 11, one-piecespring clamps 46 are formed, which can be hooked onto the crosspieces 23and 24 via an upper holding groove 47. Aside from the holding groove 47,the spring clamp 46 has an actuating lever 48, which forms a lockingnose (not illustrated). Said locking nose can lock with a locking noseor locking recess (not illustrated, either) below the crosspiece 23 and24, respectively, the spring clamp 46 engaging behind the crosspieces 23and 24. The elastic spring clamp 46, which is made of plastic, can bedetached from the cross pieces 23 and 24 by pushing the actuating lever48. In this way, a connecting section 49 of the spring clamp 46, whichconnects the holding groove 47 to the actuating lever 48, is bent openfar enough for the locking connecting 43 to be released and the springclamp 46 to be removable from the crosspieces 23 and 24. In particularrealizing the locking connection 43 under a spring tension caused by thespring clamp makes it possible for the polarization filter devices 11 tobe attached to the crosspieces 23 and 24 with zero play and in an easilyworkable manner.

The polarization filter devices 11 each have a circular or a linearpolarization filter 91. The linear polarization filter 91 shown here canbe pivoted in and out in front of the lens holder devices 12 and 13 bymeans of a hinge 93 of the polarization filter device 11. Furthermore,the polarization filter is rotatable in front of the lens holder devices12 and 13 about an axis 92 of the polarization filter device 11 in sucha manner that a direction of polarization of the linear polarizationfilter 91 can be switched.

The lens holder devices 12 and 13 each have a rotatable ring 50 and 51,respectively, in which four front or ventral lens seats 52 and 53,respectively, are arranged. Furthermore, two rear or dorsal lens seats54 and 55 are arranged on the lens holder devices 12 and 13,respectively. The front lens seats 52 and 53 are formed by crosspieces56, 57 and 58, the crosspieces 56 and 57 having pressure fingers 59 forclamping insert lenses (not illustrated). The pressure fingers 59 aresubjected to a contact pressure force via a shared leaf spring 60.

Each of the rings 50 and 51 can be manually turned via a rotatableactuating shaft 61 having an operating element 62 and can be adjustedwith the aid of a scale division of 2.5° to an angle of a cylinder of aninsert lens, for example. To prevent unintentional adjustment of therings 50 and 51, a braking means 63 is formed on the actuating shaft 61.The braking means 63 is formed by an eccentric plastic ring 64, whichsurrounds the actuating shaft 61 and by whose radial rotation on theactuating shaft 61 a larger or smaller rotating resistance of theactuating shaft 61 can be set by choice.

A combined view of FIGS. 8 to 12 shows a spindle gear 65 for the lensholder devices 12 and 13, having a threaded spindle 66, an inner bearing67 and an outer bearing 68 and an operating element 62. A threadedsection 69, to which the threaded spindle 66 is engaged, is molded toeach of the lens holder devices 12 and 13. A rotation of the threadedspindle 66 consequently causes an adjustment of the lens holder device12 or 13 in the transversal direction. The bridge sections 15 and 16 areformed by an extruded profile 70 made of aluminum, the extruded profile70 having a passage bore 71 into which the threaded spindle 66 isinserted with the inner bearing 67. The threaded spindle 66 merely needsto be inserted into the passage bore 71 together with the lens holderdevices 12 and 13 and the outer bearing 68 and the inner bearing 67. Theouter bearing is secured by means of a screw (not illustrated). Alongitudinal slot 72, which forms parallel guide surfaces 73 for sidesurfaces 74 of the lens holder devices 12 and 13, is connected to thepassage bore 71. A guide groove 75 is formed in each of the guidesurfaces 73. The lens holder devices 12 and 13 form guide protrusions 76and 77, which engage into the guide grooves 75. The guide grooves 75themselves thus form guide surfaces 78 for the guide protrusions 76 and77. In this way, a particularly stable and zero-play guiding of the lensholder devices 12 and 13 in a thus formed guide means 79 is ensured, theguide means 79 being particularly easy to produce.

All operating elements 62 are always frustoconical and made in one pieceof a flexible plastic material, as illustrated by the example of thethreaded spindle 66, and are simply plugged onto an actuating end 80.The actuating end 80 has a fitting surface 81 for transmit-ting a torqueand a locking recess 82 for securing the operating element 62.

A combined view of FIGS. 13 to 16 shows the adjustment gear 20 of thenose rest device 18 having a toothed rack 83 and a bevel worm wheel 84and the nose rest 19. The adjustment gear 20 is received in a housing 85and connected to the pivot axis 17 via said housing 85. The nose restdevice 18 is adjusted via the adjustment gear 20 by manual actuation ofthe operating element 62, which is plugged onto an actuating shaft 88 ofthe bevel worm wheel 84. The bevel worm wheel 84 has an opening angle αof 90°, the bevel worm wheel 84 thus being arranged at an angle β of 45°relative to the toothed rack 83. As a consequence, the operating element62 of the bevel worm wheel 84 is always arranged above a transversalplane 86 of the bridge 14. When the nose rest device 18 is adjustedalong with the housing 85 on the pivot axis 17 of the bridge 14, alongitudinal axis 87 of the bevel worm wheel 84 is still always inclinedby an angle γ>0° in relation to the transversal plane 86. The operatingelement 62 of the bevel worm wheel 84 is thus always located outside orat the edge of a subject's field of vision and is easily accessible toan operator. Moreover, the position of the operating elements 62 doesnot interfere with an exchange of insert lenses (not illustrated).

The bevel worm wheel 84 is molded to the actuating shaft 88 in onepiece. The operating element 62 is plugged onto the actuating shaft 88.The toothed rack 83 is bent at a lower end 89 and has a receiving axis90. The nose rest 19, which is made of a flexible plastic material, ismerely plugged onto the receiving axis 90. In this way, the nose rest 19can be easily replaced, if needed.

The invention claimed is:
 1. A trial frame for determining thesubjective refraction of a subject, comprising: first and second lensholder devices for receiving insert lenses; a bridge, which connects thefirst and second lens holder devices in such a manner that theirdistance relative to each other is adjustable; a nose rest device havinga pivotable and height-adjustable nose rest; first and second temples,which are adjustable in a length and a height dimension, the trial framecomprising first and second polarization filter devices, each of thefirst and second polarization filter devices having a circular or alinear polarization filter, and a pivot for pivoting the circular orlinear polarization filter in and out in front of the corresponding oneof the first and second lens holder devices and a rotating device forrotating the polarization filter in front of the corresponding one ofthe first and second lens holder devices, the polarization filterdevices each being removably attachable to the corresponding one of thefirst and second lens holder devices through a locking connection; and aone-piece spring clamp formed on an attachment end of a holder of atleast one of the polarization filter devices, said spring clamp engagingbehind a crosspiece molded to each of the corresponding one of the firstand second lens holder devices, and an actuating lever molded to thespring clamp and configured to selectively open the spring clamp.
 2. Thetrial frame according to claim 1, wherein the nose rest device has anadjustment gear for adjusting the height of the nose rest, theadjustment gear having a toothed rack and a bevel worm wheel, which areengaged with each other.
 3. The trial frame according to claim 2,wherein the adjustment gear is formed by the toothed rack and the bevelworm wheel.
 4. The trial frame according to claim 2, wherein the bevelworm wheel has an opening angle α of 60° to 120°.
 5. The trial frameaccording to claim 4 wherein the bevel worm wheel has an opening angle αof 90°.
 6. The trial frame according to claim 2, wherein the bevel wormwheel has a lead of 1 mm to 3 mm.
 7. The trial frame according to claim6, wherein the bevel worm wheel has a lead of 2 mm.
 8. The trial frameaccording to claim 2, wherein the bevel worm wheel is molded to anactuating shaft, wherein an operating element can be plugged onto theactuating shaft.
 9. The trial frame according to claim 8, wherein theoperating element is arranged above the bridge.
 10. The trial frameaccording to claim 8, wherein the operating element is cylindrical orfrustoconical in shape and is made in one piece of a flexible plasticmaterial.
 11. The trial frame according to claim 1 wherein the nose restdevice is mounted on a pivot axis of the bridge with a radial clamping.12. The trial frame according claim 1 wherein the bridge is formed byfirst and second bridge sections, which are firmly connected with apivot axis, the nose rest device being pivotably mounted on the pivotaxis.
 13. The trial frame according claim 1 wherein the bridge and thefirst and second lens holder devices together form a guide for guidingthe first and second adjustable lens holder devices in the longitudinaldirection of the bridge, the bridge having a spindle gear including athreaded spindle for distance adjustment of the first and second lensholder devices, at least one guide protrusion being formed on each ofthe first and second lens holder devices which engages into a guidegroove formed in the bridge, open threaded sections being formed on eachof the first and second lens holder devices, the threaded spindle beingengaged with the threaded section.
 14. The trial frame according toclaim 1 wherein the first and second lens holder devices each have arotatable ring, on which corresponding first and second lens seats areformed, an actuating shaft of each ring having an adjustable brakecomprising an eccentric plastic ring.
 15. The trial frame according toclaim 1 wherein the first and second lens holder devices each have fourfront and two rear lens seats.
 16. The trial frame according to claim 1wherein each lens seat of the first and second lens holder devices hasat least one pressure finger for clamping an insert lens, the respectivepressure fingers being arranged in a row on the lens holder device andbeing subjectable to a contact pressure force via a shared leaf spring.17. The trial frame according to claim 1 wherein each temple end of thefirst and second temples is flexible and loop-shaped.
 18. The trialframe according to claim 1 wherein each temple end of the first andsecond temples is formed in one piece and a portion is made of a softplastic and a portion is made of a hard plastic material.
 19. The trialframe according to claim 1 wherein a ventral end of the temple iscranked.